Apparatus for inhibiting explosive mixing of liquid natural gas and water

Abstract

Fluid-fluid explosive self-mixing of water and liquid natural gas contained in a cryogenic tank located in a hold of a ship is inhibited, in the event that the hold of the ship and the cryogenic tank are ruptured, by confining an inert gas under pressure in a multiplicity of tubes surrounding the cryogenic tank, the pressure of the inert gas in the tubes being such that the inert gas flows from the tubes to form a blanket of inert gas between liquid natural gas and water upon rupture of any tube or tubes.

I claim: 
     
       1. An apparatus for inhibiting fluid-fluid explosive self-mixing of cryogenic fluid contained in a cryogenic tank and water in proximity to the tank, in the event of rupture of the cryogenic tank, comprising a multiplicity of tubes surrounding the cryogenic tank, a source of an inert gas connected to the tubes, thermal insulation between the tubes and the tank to prevent liquefication of the inert gas contained in the tubes and means for confining and maintaining the inert gas under pressure in the tubes, the pressure of the inert gas in the tubes being substantially higher than the highest water pressure to which the cryogenic fluid may be subjected in the event of rupture of the tank such that the inert gas flows from the tubes and forms a blanket of inert gas between cryogenic fluid and water upon rupture of any tube or tubes. 
     
     
       2. An apparatus according to claim 1, wherein the inert gas is flue gas (CO 2  + N 2 ) and the source thereof is a combustion process. 
     
     
       3. An apparatus according to claim 1, wherein the pressure of the inert gas in the tubes is in the order of about 100 to about 200 psi. 
     
     
       4. An apparatus according to claim 1, wherein the cryogenic tank is located in or on a ship, the inert gas is flue gas (CO 2  + N 2 ) and the source thereof is a combustion process. 
     
     
       5. A method of inhibiting fluid-fluid explosive self-mixing of a cryogenic fluid contained in a cryogenic tank and water in proximity to the tank, in the event that the tank is ruptured, comprising the step of confining and maintaining an inert gas under pressure in a multiplicity of tubes located close to each other and surrounding the tank and thermally insulated from the tank to prevent liquefication of the inert gas contained in the tubes, the pressure of the inert gas in the tubes being substantially higher than the highest water pressure to which the cryogenic fluid may be subjected in the event of rupture of the tank such that the inert gas flows from the tubes and forms a blanket of inert gas that inhibits forced contact between the cryogenic fluid and the water upon rupture of any tube or tubes. 
     
     
       6. A method according to claim 5, wherein the inert gas is maintained at a pressure in the order of about 100 to about 200 psi.